Liquid projectile launcher

ABSTRACT

A fluid projectile launcher ( 10 ) comprises a barrel having an open end and a closed end defining a breech portion ( 50 ). The breech portion ( 50 ) is arranged to hold a dosage of fluid ( 56 ) in the form of an ionizing medium for rendering the fluid electrically conductive and an active substance which induces a physiological reaction in living organisms. The projectile launcher ( 10 ) includes a launching initiation circuit in the form of a capacitor ( 22 ) and an inductance ( 36 ), and a pair of electrodes ( 38 A,  38 B) forming part of the breech portion ( 50 ). Trigger means ( 40 ) are provided for allowing the energy storage means ( 22 ) to discharge into the dosage of fluid ( 56 ) in the breech portion ( 50 ) via the electrodes ( 52, 38 A,  38 B) so as to cause the dosage of fluid ( 56 ) to be projected from the open end of the barrel as a fluid projectile. The leads ( 38 A,  38 B) connecting the capacitor ( 22 ) and inductance ( 36 ) are arranged in a radially symmetrical pattern about a tubular first electrode so as to create an electromagnetic field which is functionally symmetrical in the plane normal to the central axis of the barrel. The launcher may be in the form of a portable hand held device.

BACKGROUND TO THE INVENTION

A number of applications clearly show that water droplets projected athigh velocity can retain their integrity until impacting on a desiredtarget a selected distance away. For example, cutting machines usinghigh pressure air and/or water jets have been successfully used for manyyears. Vaccination guns based on hydraulic propulsion have also becomecommonplace. Due to the number of conversions prior to application,energy is, however, not always utilised efficiently.

Direct energy conversion from electrical to kinetic has been applied inthe case of metallic projectile launchers utilising a successivelypulsed array of solenoid coils to provide the requisite acceleratingforce. It has also been applied in conjunction with a water propellantto effect the discharge of a small gun—the water first having been madeconductive by the addition of salt—and by passing through an electricalcurrent to bring about an electric arc, thereby promoting the requisitesurge of electric current required to eject a solid projectile from thebarrel at high velocity.

A water-arc launcher utilising this principle is described in a magazinearticle by Peter Graneau. Electronics and Wireless World, June 1989, pp556-559. However, the side-mounted current connector in this versionresults in pronounced asymmetry in the axial current flow uponlaunching, causing the liquid charge to scatter widely upon emergingfrom the barrel, and thereby rendering the device ineffective for use asa globular liquid projectile launcher. The use of a solid projectile inconjunction with the water charge incorporated in the water gun featuredin this article is also somewhat impractical. While the water chargeamounts to a rather modest 3.8 g, the energy requirement to propel thetotal charge at 1000 meters per second would necessitate capacitorcharge to a voltage sufficient to sustain an electric arc, amounting toa half to a full farad of capacitance, and capable of discharging insizable fractions of 100 kA. This would weigh many kilograms, and makeequipment based on this type of approach too heavy for use inapplications requiring a high degree of portability.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a fluidprojectile launcher comprising a barrel having an open end and a closedend defining a breech portion arranged to hold a dosage of fluid, and alaunching initiation circuit including energy storage means, energyapplication means forming part of the breech portion, symmetricalthrust-generating and perpetuating means, and trigger means for allowingthe energy storage means to discharge into the dosage of fluid in thebreech portion via the energy application means so as to cause thedosage of fluid to be symmetrically thrusted from the open end of thebarrel as a fluid projectile.

Preferably, the energy application means includes first and secondelectrodes which are insulated from one another bar their individualelectrical connection via the dosage of fluid, and which are symmetricalabout a central axis of the barrel, the energy storage means includes acapacitor, and the symmetrical thrust generating and perpetuating meansincludes an array of electrical leads connected symmetrically to thefirst and second electrodes relative to the central axis of the barrelso as to create an electromagnetic field which is functionallysymmetrical in a plane normal to the central axis of the barrel.

Conveniently, the breech portion is dimensioned and the energyapplication means is positioned to accommodate a fluid dosage having amaximum mass of 1 gram.

Advantageously, the breech portion includes a tubular electricallyconductive portion defining the first electrode, the second electrodecomprises an electrically conductive pin substantially coincident withthe central axis of the barrel and extending into a base of the breechportion, and the array of electrical leads including at least a firstpair of leads connected equi-angularly in a radially symmetrical patternaround the tubular first electrode and a second lead connected to thesecond electrode.

The invention extends to a fluid projectile launcher comprising a barrelhaving an open end and a closed end defining a breech portion arrangedto hold a dosage of fluid, and a launching initiation circuit includingenergy storage means, energy application means forming part of thebreech portion, and trigger means for allowing the energy storage meansto discharge into the dosage of fluid in the breech portion via theenergy application means so as to cause the dosage of fluid to belaunched from the open end of the barrel as a fluid projectile, thebreech portion being dimensioned and the energy application means beingpositioned to accommodate a fluid dosage having a maximum mass of 1gram, preferably having a maximum mass of 0.5 grams, and more preferablyhaving a maximum mass of 0.1 grams.

Typically, the energy storage means includes a capacitor and aninductance for controlling the rate of discharge of arc current acrossthe first and second electrodes, the arc current having a waveformincluding at least one half sinusoid.

The waveform of the discharge arc current may include a plurality ofhalf sinusoids defining at least one damped oscillation.

Preferably, the launching initiation circuit includes a pair of inputterminals arranged to be connected to a power supply, and conditioningmeans for conditioning the power from the power supply, the conditioningmeans including a voltage multiplying rectifier.

The fluid projectile launcher may be in the form of a portable hand-helddevice including a handle, and the trigger means includes a slidingswitch having a pair of fusible contacts, and a separator for pryingopen the contacts after use.

The barrel may have a diameter from 2 mm to 3.5 mm.

According to a still further aspect of the invention there is provided aprimed fluid projectile launcher comprising a barrel having an open endand a closed end defining a breech portion holding a dosage of fluid,and a launching initiation circuit including energy storage means,energy application means forming part of the breech portion, and triggermeans for allowing the energy storage means to discharge into the dosageof fluid in the breech portion via the energy application means so as tocause the dosage of fluid to be launched from the open end of the barrelas a fluid projectile, the dosage of fluid comprising an ionising mediumfor rendering the fluid electrically conductive and an active substancewhich induces a physiological reaction in living organisms.

The active substance may include at least one of the following, namely adrug, a plant or animal protection agent such as a vaccine orinsecticide, a nutrient, a poison, a pain-inducing substance, or adisabling agent.

The invention extends to a method of inducing a physiological reactionin a living organism including the steps of providing a fluid projectilelauncher comprising a barrel having an open end and a closed enddefining a breech portion, and a launching initiation circuit includingenergy storage means, energy application means forming part of thebreech portion, and trigger means, loading the breech portion of thefluid projectile launcher with a dosage of fluid, the fluid including anionising medium for rendering the fluid electrically conductive and anactive substance which induces a physiological reaction in the livingorganism, aiming the liquid projectile launcher at a target defined bythe living organism, and activating the trigger means so as to allow theenergy storage means to discharge into the dosage of fluid in the breechportion via the energy application means so as to cause the dosage offluid to be thrusted from the open end of the barrel as a fluidprojectile.

The method may include the initial step of charging the energy storagemeans from an external power supply.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below, by way of exampleonly, and with reference to the accompanying drawings in which:

FIG. 1 is a schematic and circuit diagram of a liquid projectilelauncher of the invention; and

FIG. 2 is a cross-sectional side view of one embodiment of a typicalliquid projectile launcher of the invention.

DESCRIPTION OF EMBODIMENTS

Referring first to FIG. 1, a liquid projectile launcher 10 has threemain components, namely a voltage tripling rectifier indicated in brokenoutline at 12, an energy storage device indicated in broken outline at14 and a barrel and breech assembly indicated in broken outline at 16.

An AC utility supply typically having a potential of 240 volts at afrequency of 50 hertz is briefly connected across input terminals 18 and20 of the voltage tripling rectifier 12. The voltage tripling rectifierallows the capacitor 22 to charge to approximately 1 kV. In analternative version of the invention, a battery supply is used as apower source to charge the capacitor 22, in which case an inverter needsto be included to provide the necessary AC supply across the terminals18 and 20.

The voltage tripling rectifier works in the following manner. If thepotential at terminal 18 is positive and rising in respect of terminal20, diode 24 conducts so as to charge a capacitor 26, with a smallcurrent flowing via a bridging resistor 28. As soon as the polarity atthe terminals 18 and 20 is reversed, this causes a diode 30 to conductthereby charging a capacitor 32. On the following reversal, both diode34 and diode 30 conduct, and the main energy storage capacitor 22 willbe partly charged. Thereafter, successive reversals of the AC supplywill pass a certain amount of charge via the capacitor “bucket brigade”,until the energy storage capacitor 22 is fully charged after a fewseconds.

The capacitors 26 and 32 have typical values of 1 to 5 microfarads,whilst the main charge storage capacitor 22 has a value of between 100and 250 microfarads, depending on the charge required to launch theliquid projectile. The diodes 24, 30 and 34 are typically inexpensivelow current devices rated at about 1.2 kV PIV. It is essential that thediode 34 has a very low reverse leakage at full applied peak reversevoltage so as to prevent discharge of the main charge storage capacitor22 after charging is complete and the device is disconnected from thepower source. The resistor 28 ensures that there will be zero potentialacross the terminals 18 and 20 once they are unplugged from the powersource by providing a discharge path for the capacitors 26 and 32.

The main energy storage capacitor preferably comprises a metallisedplastic film capacitor, and may alternatively be in the form of a highcurrent electrolytic capacitor or ceramic capacitor. The main criteriaof the capacitor 22 being that is should have a high dischargedelivering capability, low leakage, modest self-inductance and thesmallest possible physical dimensions.

The inductance 36 may be entirely incorporated into the self-inductanceof the capacitor 22, together with the interconnecting lead inductanceof the entire energy storage circuit indicated in chain outline at 38,and including electrode leads 38A and 38B defining split, but equalcurrent paths which form an effective closed loop on closure of triggerswitch 40. Alternatively, the inductance may include a specific inductorincorporated conveniently in series with the other inductances. As ismore clearly illustrated in FIG. 2, the switch 40 comprises a pair ofbroad contacts in the form of a fixed contact 40A and a hinged contact40B which are brought into contact with one another by bringing suitablepressure to bear against a sliding mechanism 42 in the direction ofarrow 43. Under-engineering of the switch contacts 40A and 40B is notnecessarily a disadvantage, in that on closure, the current across theswitch contacts will cause partial welding of the mating faces, therebypreventing contact bounce and also ensuring low contact resistance. Awedge-shaped separator 44 extends rearwardly from a front end of theslider 42 so as to pry open the contacts 40A and 40B after use. Anadditional contact cleaning mechanism may be used in applications wherefrequent use of the liquid projectile launcher is required.

The barrel and breech assembly 16 is in the form of a tube having afront electrically insulating portion 48 and a rear electricallyconductive breech portion 50 serving as a first electrode. The leads 38Aand 38B terminate in diametrically opposed connection points 51A and 51Bon the outer perimeter of the breech portion 50, adjacent the insulatingportion 48. The symmetry of the electrical connection relative to theaxis of the tube allows for an axial propulsion current which issubstantially symmetrical about the inner circumference of the firstelectrode 50.

Located at the base of the breech portion 50 is an electricallyconductive pin 52 which acts as a second electrode positioned centrallyalong the axis of the tube so as to co-operate advantageously with thefirst electrode to produce a symmetrical current and consequentsymmetrical thrust behind the liquid projectile upon launching. Thissecond electrode is surrounded by a spacing insulator and mechanicalbuffer 54 formed from highly resilient impact resisting material. It maybe desirable to connect the inductor 36 close to the open end ofassembly 16, in which case the electrically insulating portion 40 may beshortened or even omitted while at the same time the conductive breechportion 50 may be extended in its place.

The first, and smaller portion of the energy applied to the electrodes50 and 52 raises the temperature of a tiny fraction of water between theelectrodes to that required to form plasma, being in the order of 3000to 6000° C., with the balance and larger portion delivering therequisite thrust to accelerate the water and to drive it out of thelaunch assembly 16 at high speed. The process of heating, forming plasmaand ejection follows in a naturally, self-regulating sequence uponapplication of the high voltage potential. Symmetrical currentdistribution ensures practically all the water is ejected in globularform, remaining intact until impacting the selected target at highvelocity.

The rate of rise of pressure against the inner breech and tube assembly46 is exceptionally high, with the result that particularly resilientmaterial, such as high impact resisting nylon or polycarbonate plasticis required.

Upon discharge of the capacitor 22, the arc current easily exceeds 25000amperes, resulting in immense acceleration being applied to the liquidslug 56, which can propel the liquid from the barrel at a velocityexceeding 1000 m/s. The actual velocity depends on the size of the bodyor slug of liquid 56, the quality of finish of the inside bore of thebarrel, the symmetry of current flow in the barrel and the amount ofenergy stored in the capacitor 22.

The performance of a well-crafted liquid projectile launcher can bepredicted with a reasonable degree of accuracy.

Assuming a single drop of water is to be accelerated to 1000 meters persecond, the energy required will be: $\begin{matrix}{E = {{½\quad {mv}^{2}\quad {where}{\quad \quad}E} = {{energy}\quad {in}\quad {joules}}}} \\{\quad {m = {{mass}\quad {in}\quad {kg}}}} \\{\quad {v = {{velocity}\quad {in}\quad {m/s}}}}\end{matrix}$

Assuming there are 20 drops of water in a milliliter, thus:$E = {{\frac{1}{2} \times \frac{0.05}{1000} \times 1000^{2}} = {25\quad {joules}}}$

Assuming a mechanical efficiency of 50%, and an electrical efficiency of75%, the energy stored in the capacitor must be${25 \times \frac{100}{50} \times \frac{100}{75}} = {67\quad \text{joules}}$

The energy stored in a capacitor is: $\begin{matrix}{E = {{½\quad {CV}^{2}\quad {where}{\quad \quad}E} = {{energy}\quad {in}\quad {joules}}}} \\{\quad {C = {{capacitance}\quad {in}\quad {farads}}}} \\{\quad {V = {{potential}\quad {in}\quad {volts}}}}\end{matrix}$

Assuming the capacitor is charged to 1000 volts, then:$C = {{2\frac{E}{V^{2}}} = {\frac{2 \times 67 \times 10^{6}}{1000^{2}} = {134\quad \mu \quad F}}}$

A capacitor with the nearest standard value, being 150 μF, wouldprobably be used.

The advantage of employing high voltage is reduced capacitance. Forexample, at 2000 volts the capacitance would be:$\frac{2 \times 67 \times 10^{6}}{2000^{2}}\quad = {33.5\quad {\mu F}}$

A doubling in voltage resulting in a quartering of the capacitance valuerequired implies that the use of some tens of thousands of volts may beadvantageous. A 150 μF, 1000V dc capacitor is not too large forincorporation into a hand-held appliance, however.

Inductor 36 is included to provide a means for controlling the arccurrent, and thereby tailoring the rate of accelerating to particularcircumstances. The inductor could possess a value in the order of a fewtenths up to several μH. It may be desirable to vary the acceleration inorder to obtain a desired effect on the spread of the liquid projectilein flight, in which case the value of inductance could be increased ordecreased, as appropriate.

Assuming a capacitance of 150 micro farads, and an inductance of 0.5micro-henries, then the resonant frequency would be:$F_{res} = {\frac{1}{2\pi \sqrt{LC}} = {18.4\quad {Khz}}}$

The polarity of the arc current would then reverse every 27.2micro-seconds, in a damped oscillation.

At low inductance, the elasticity of the launch tube assembly would beseverely tested, and it may prove advantageous to increase theinductance significantly, and at the same time lengthen the conductingportion of the barrel to allow for the increased time required for theliquid projectile to achieve the desired velocity.

It may be desirable to launch the liquid projectile within the time ofthe first half sinusoid, in which case the length of the conductivebreech portion 50 would have to be tailored to provide a conductive pathwhile the projectile accelerates from stand-still to 1000 meters persecond, in, for example, 27.2 microseconds. This would involve sometrial and error work since the rate of acceleration is influenced bydiameter-to-length ratio of the barrel assembly, as well as the pin 42and buffer 54 dimensional aspects, material resilience and arc current.

Conversely, the projectile may be accelerated over, say, five halfsinusoids, in which case the projectile would take 136 micro-seconds toreach maximum speed, which is likely to be considerably less than 1000meters per second, and the launch tube would typically be much longerand narrower. The projectile would be subjected to a series of impulsesof rapidly diminishing strength, thereby varying the shape of theemerging liquid projectile.

It is important to bear in mind that electric arcs do possesscomparatively stable voltage characteristics, having an impedance whichtends to vary inversely with current. The arc voltage lies in the regionof 60 volts, and would rise only marginally with increase in current andwith increase in arc length.

As the energy stored in the capacitor 22 oscillates via the inductor 36and the arc load, it is dissipated in the arc and the associatedcircuitry resistance. This LC circuit forms an approximate constantpower source providing an efficient means of transforming a high voltagesource with a falling characteristic to a comparatively steady 60 voltsacross the arc.

Referring now to FIG. 2, a typical liquid projectile gun 64 is shown.The gun 64 resembles a conventional hand-held flashlight having anon-threatening appearance, which may enhance its effectiveness as apersonal self-defence weapon.

The barrel and breech assembly 46 occupies the same position as wouldnormally be occupied by a flashlight bulb, and the illusion is enhancedby the inclusion of a reflector 66. The sliding switch 42 is housedbeneath the plastics or rubber covering 68, which forms part of arubberised housing 70 closely resembling a conventional flashlighthousing.

The capacitor 22 is housed in the handle portion of the gun, which isnormally where the batteries of a similar flashlight are housed.Electrical connections to the capacitor 22 are made via conductive endplates 72 and 74, with parallel leads 76A and 76B, (corresponding tocurrent paths 38A and 38B respectively), having substantially matchingresistive as well as inductive characteristics, extending from the endplate 72 to the inductor 36 and the hinged terminal 40B extendingdirectly from the end plate 74.

In the present embodiment the leads 76A and 76B are diametricallyopposed with respect to the central axis of the breech and tube assembly46. A favourable reduction in circuit resistance, as well as inductance,together with an improvement in the current flow symmetry is achieved byincreasing the number of paralleled conductors, for example, to threeconductors radially equi-spaced at 120° from one another, to four spacedat 90° from one another, and by logical extension arriving at asubstantially enclosing coaxial arrangement for best possible results.

The voltage tripling rectifier circuit 12 is housed behind the reflector66 opposite the inductor 36. The input terminals 18 and 20 are locatedwithin recesses 78 and 80 located at the outer periphery of thereflector 66, and are arranged to mate with a special power sourceadaptor (not shown) so as to provide contact between the terminals 18and 20 and the utility power source so as to charge the capacitor 22.

In use, the gun is held in the manner of a flashlight, and is aimed atthe desired target. The sliding mechanism 42 is operated by pressing thethumb forward against the rubber cover 68 in the direction of the arrow43. As was described previously, return of the sliding mechanism 42separates the contacts of the switch 40.

Replenishment of liquid 56 is carried out by means of a suitabledispenser, which is calibrated so as to deposit a correctly measureddose of liquid into the barrel and breech assembly 46. It is clear fromthe above description that the gun requires manual recharging beforeeach successive discharge. It is possible to achieve a degree ofrepetition by constructing an appropriate feeding system incorporating aliquid reservoir or magazine so as to automatically replenish the liquidas well as recharging the capacitor 22 after each successful operation.Alternatively, a multiple barrel-capacitor system may be devised. As theliquid projectile launcher of the invention is electrically detonated,this makes it particularly well suited to remote detonation.

Several different barrel constructions are possible. In one alternativeconstruction, the non-conductive barrel portion 48 may be replaced witha conductive portion which extends from the conductive breech portion50. As a further option, additional barrel sections may be provided forproviding additional guidance and velocity to the liquid projectile.These barrel sections may include electrically conductive and insulatingsections which are fitted alternately to one another, whereby theconductive sections provide an additional accelerating force for theliquid projectile, being optionally connected to additional energystorage circuits.

In a particular embodiment, the conductive breech portion may beconstructed of solid metal. Alternatively, it may be constructed of anon-conductive material, for example, plastic, having a metal lininginside the bore, extending outwards where required for the electricalconnection.

In another embodiment described, the inner barrel diameter may bebetween 2 to 3.5 mm and the overall barrel length may be from 20 to 50mm so as to accommodate a single drop (0.05 ml) of water. Naturally,depending on the rating of the energy source, these dimensions may bescaled up or down.

In a further embodiment the bobbin of the capacitor 22 may be enlargedsufficiently to allow the entire tubular barrel assembly 46 to be housedinside the inner bore of the capacitor bobbin thereby reducing theeffective length of the interconnections and maximising efficiency.

It seems unlikely that, on its own, a single drop of water will have asignificant effect on a human or animal target. Certainly, a drop ofwater travelling at 1000 m/s, which is about three times the speed ofsound, will pass through all but the heaviest clothing and will easilypass through hair or fur. The addition of reasonable strong acid. (pHless than about 3), or reasonably strong base, (pH greater than about11), can alter the effect dramatically, by providing a pain stimulus ofgreat intensity upon being driven into the skin. Such acids wouldinclude all the strong mineral acids as well as organic acids such asformic acid. Even the acid constituents of a mild acid such as orangejuice could suffice. Bases such as ordinary washing soda, ammonia, andthe like would be equally effective. Common solvents such as acetonecould also provide a pain stimulus. By way of illustration, the effectof application of any of these substances to, say, a small cut in thefinger, is well known.

The addition of organic irritation-specific substances or pharmaceuticaldrugs possessing pain inducing properties may prove advantageous. Thesemay include capsaicin, a compound obtained from chili peppers—capsicumminimum—which causes a fierce burning sensation. Substances found in thestings of bees, wasps and hornets, and indeed the common nettle, whichinclude histamine, serotonin and acetylcholine, acting in concert, caninduce instant severe pain, despite the almost infinitesimal amounts ofactive component involved. Histamine is highly effective since it mimicsthe body's very own pain inducing stimulation process.

Histamine is conventionally dispensed in the form of histaminedisphosphate, C₅H₉N₃.2H₃PO₃, or as the dihydrochloride salt, although itis light-, as well as temperature-sensitive.

The effect on an attacker from a discharge, at short to medium range, islikely to be immediate and profound. Firing results in a bright flash oflight, a loud audio report followed immediately by the onset of intenselocalised pain. The combination provides a convincing simulation offirearm discharge. In the case of some irritation-specific substances, alocalised entry wound may take the form of a burn or a weal. Inaddition, there may be a generalised reaction to these substancesresulting in shock with associated mental impairment. Significantly,these conditions are generally reversible.

It may be advantageous to use the present liquid projectile launcher inthe application or administration of anaesthetics, tranquilizers, andthe like, as well as other drugs of a preventative nature—even dyes andcolorants—to human as well as animal recipients.

Unwanted interaction between electrically induced activity and thesubstances included in the liquid projectile may be minimised byinclusion of specific barrier arrangements applied and/or located tomaintain desired separation.

In the case of dyes, colourants, as well as other substances used forsurface treatment of objects, an effectively continuous feed of theprojected substance may be employed, including a means of providingcorresponding electrical energy required by the process. The liquid fordispensing is fed into the mechanism in sequential doses, each dosebeing individually launched by carefully timed electrical discharges, athigh speed, to provide an effect of continuity of feed.

What is claimed is:
 1. A fluid projectile launcher, comprising a barrelhaving an open end and a closed end defining a breech portion arrangedto hold a dosager of fluid, and a launching initiation circuit includingenergy storage means, energy application means forming part of thebreech portion, symmetrical thrust-generating and perpetuating means,trigger means for allowing the energy storage means to discharge intothe dosage of fluid in the breech portion via the energy applicationmeans in the form of an arc current so as to cause the dosage of fluidto be symmetrically thrusted from the open end of the barrel by thesymmetrical thrust-generating and perpetuating means as a fluidprojectile, and discharge control means for controlling the rate ofdischarge of arc current across the energy application means, the breechportion being dimensioned and the energy application means beingpositioned to accommodate a discrete fluid dosage having a predeterminedmass.
 2. A fluid projectile launcher according to claim 1 in which theenergy application means includes first and second electrodes which areinsulated from one another bar their individual electrical connectionvia the dosage of fluid, and which are coaxial with a central axis ofthe barrel, the energy storage means includes a capacitor, the dischargecontrol means includes an inductance and the symmetricalthrust-generating and perpetuating means includes an array of electricalleads connected symmetrically to the first electrode with respect to aplane which is normal to the central axis of the barrel so as to createan electromagnetic field which is functionally symmetrical in such aplane.
 3. A fluid projectile launcher according to claim 2 in which thebreech portion includes a tubular electrically conductive portiondefining the first electrode, the second electrode comprises anelectrically conductive pin substantially coaxial with the central axisof the barrel and extending into a base of the breech portion, and thearray of electrical leads includes at least a first pair of leadsconnected equi-angularly in a radially and axially symmetricalconfiguration around the tubular first electrode, and a second leadconnected to the second electrode.
 4. A fluid projectile launcheraccording to claim 1 in which the energy storage means includes astorage capacitor, the discharge control means comprises an inductanceand the arc current has a discharge waveform including at least one halfsinusoid.
 5. A fluid projectile launcher according to claim 4 in whichthe discharge waveform of the arc current includes a plurality of halfsinusoids defining at least one damped oscillation for subjecting theliquid projectile to a series of impulses of diminishing strength.
 6. Afluid projectile launcher according to claim 1 in which the launchinginitiation circuit includes a pair of input terminals arranged to beconnected to a power supply, and conditioning means for conditioning thepower from the power supply, the conditioning means including a voltagemultiplying rectifier.
 7. A fluid projectile launcher according to claim6 in which the power supply is an external AC mains supply.
 8. A fluidprojectile launcher according to claim 6 in which the power supply is aninverted battery supply.
 9. A fluid projectile launcher according toclaim 6 in which the voltage multiplying rectifier comprises first andsecond charging capacitors which are alternately charged via respectivefirst and second diodes so as to successively build up charge in thestorage capacitor.
 10. A fluid projectile launcher according to claim 1which is in the form of a portable hand-held device including a handle,and the trigger means includes a sliding switch having a pair of fusiblecontacts, and a separator for prying open the contacts after use.
 11. Afluid projectile launcher according to claim 1 in which the barrel hasan internal diameter from 2 mm to 3.5 mm.
 12. A fluid projectilelauncher according to claim 1 in which the barrel has an effectivelength of 20 mm to 50 mm.
 13. A primed fluid projectile launchercomprising a barrel having an open end and a closed end defining abreech portion holding a dosage of fluid, and a launching initiationcircuit including energy storage means, energy application means formingpart of the breech portion, and trigger means for allowing the energystorage means to discharge into the dosage of fluid in the breechportion via the energy application means in the form of an arc currentso as to cause the dosage of fluid to be launched from the open end ofthe barrel as a fluid projectile, and discharge control means forcontrolling the rate of discharge of arc current across the energyapplication means, the breech portion being dimensioned and the energyapplication means being positioned to accommodate a discrete fluiddosage having a predetermined mass, and the dosage of fluid comprisingan ionising medium for rendering the fluid electrically conductive andan active substance which induces a physiological reaction in livingorganisms.
 14. A primed fluid projectile launcher according to claim 13in which the substance includes one of the following, namely a drug, aplant or animal protection agent such as a vaccine or insecticide, anutrient, a poison, a pain-inducing substance, or a disabling agent. 15.A method of inducing a physiological reaction in a living organismincluding providing a fluid projectile launcher comprising a barrelhaving an open end and a closed end defining a breech portion, and alaunching initiation circuit including energy storage means, energyapplication means forming part of the breech portion, trigger means, anddischarge control means for controlling the rate of discharge of arccurrent across the energy application means, loading the breech portionof the fluid projectile launcher with a discrete dosage of fluid havinga predetermined mass, the fluid including an ionising medium forrendering the fluid electrically conductive and an active substancewhich induces a physiological reaction in the living organism, aimingthe liquid projectile launcher at a target defined by the livingorganism, and activating the trigger means so as to allow the energystorage means to discharge in a controlled fashion into the dosage offluid in the breech portion via the energy application means in the formof an arc current so as to cause the dosage of fluid to be thrusted fromthe open end of the barrel as a fluid projectile.
 16. A method accordingto claim 15 in which the active substance includes at least one of thefollowing, namely a drug, a plant or animal protection agent such as avaccine or insecticide, a nutrient, a poison, a pain-inducing substance,or a disabling agent.
 17. A method according to claim 15 which includescharging the energy storage means from an external power supply.